This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The goal of this project is to identify peptides presented by the diabetogenic MHC class II molecule I-Ag7 from NOD mice. Studies will use both NOD mice and cell lines derived from insulinomas. The study will extend to cover the effect of loading, posttranslational modification, and challenge by foreign peptides and proteins. Mass spectrometry will be used to sequence and catalog these peptides and the development of techniques to improve sensitivity and analysis will be pursued.